Duct replacement is the removal and rebuilding of a home’s supply and return ductwork, as distinct from sealing the ducts already there. TLS replaces, repairs, seals and installs residential ductwork across ten Florida counties. A full re-duct runs $2,500 to $12,000 by house size; sealing an intact system runs $1,000 to $3,000.
Call 941-269-3433 and ask Courtney for a duct assessment. A TLS technician puts a manometer across your air handler, walks every run he can reach in the attic, and leaves a written recommendation that says seal, repair or replace — with the reading that produced it.
Six signs point at the ducts rather than the equipment: one room that never cools, a house that feels clammy at the right temperature, electricity bills climbing without a change in habits, a system running almost constantly, dust settling days after cleaning, and visible sagging, torn or disconnected duct in the attic.
A duct system delivers a designed volume of air to each room, and a room running five or six degrees warmer than the rest is almost always receiving less than it was designed to receive. The usual causes are a crushed flex run, a branch off its collar, or a return undersized on the day the house was built.
Air conditioning removes humidity by pulling indoor air slowly across a cold coil. A system leaking on the return side feeds hot, wet attic air into that airstream, and the coil spends its capacity drying air it was never meant to see. The thermostat reads 74 and the house feels damp.
Duct leakage is the largest single energy loss in most Florida homes and it worsens gradually, so the bill climbs slowly enough to be blamed on rates.
An air conditioner sized correctly should cycle. One running continuously through a Pinellas Park August is usually not undersized — it is delivering a share of its air to the attic.
Ductwork under negative pressure draws attic air through every gap, carrying insulation fibres and dust into the supply airstream.
Sagging flex duct, a torn outer jacket, insulation gone grey and brittle, or a run lying disconnected on the joists. If you can see it from the hatch, it has been that way a while.
None of the six is proof alone, and all six are measurable in an hour.
Static pressure tells you whether your ductwork can move the air your equipment needs. Most residential systems carry a design maximum total external static pressure of 0.5 inches of water column, and roughly half of that budget belongs to the ducts. A reading above 0.5 means the duct system is the restriction, not the equipment.
The supply-side figure is positive pressure and the return-side figure is negative; added together they are total external static pressure, which is the number the manufacturer designed the blower around. On ductwork it is where the conversation begins rather than where it ends, because the split between the two halves says which side of the system is costing you the air.
Against that 0.5 inch design maximum, the ACHR News diagnostic standard allocates the pressure drop roughly as:
A system reading 0.9 inches with 0.45 of that in the return has told you exactly what to fix, and it is not the compressor. A blower working against double its design pressure moves far less air than its nameplate says, and a coil starved of air freezes. That is why a duct problem so often arrives disguised as an equipment problem, and why AC repair that never measures airflow gets called back to the same house.
TLS acts on four bands. Below 0.5 inches of water column the duct system is inside its design budget and needs no work on the reading alone. Between 0.5 and 0.7 there is one restriction to find. Between 0.7 and 0.9 the ducts are the limit. Above 0.9 the system cannot deliver design airflow.
| Total external static pressure | What the reading means | What TLS recommends |
|---|---|---|
| Below 0.5 in. w.c. | The duct system is inside the design budget the blower was built around | No duct work on the reading alone. If a room is still short of air, the fault is a single run or a register, not the system |
| 0.5 – 0.7 in. w.c. | One restriction, and it is usually findable in an hour | Isolate it — filter, coil, return grille or one crushed run. Sealing or a single repair normally brings it back inside budget |
| 0.7 – 0.9 in. w.c. | The duct system, not the equipment, is the limit on the airflow | Return-side rebuild or a partial re-duct, priced next to a full replacement so you can see both numbers |
| Above 0.9 in. w.c. | The blower cannot deliver the airflow the system was designed to move | Full duct assessment. Replacement is usually the honest answer, and we will say so with the reading next to it |
The reading is free on any TLS call. Where you want the number documented on its own — before a house sale, or to check what another contractor told you — a standalone duct leakage or pressure test is $200 to $450.
Where the reading is climbing rather than high, regular AC maintenance is what catches it. A static pressure figure rising across consecutive visits is a duct system degrading in slow motion, and it is on the tune-up sheet every time.
About 20 to 30 percent of the air moving through a typical duct system is lost to leaks, holes and poorly connected joints, according to ENERGY STAR. In Florida the loss is worse than the national figure because most ductwork runs through unconditioned attic space rather than inside the cooled envelope.
A Florida Solar Energy Center study measured a return leak fraction averaging 10 percent across 91 Central Florida houses, and found infiltration roughly four times higher with the air handler running than with it off — 0.93 air changes per hour against 0.21. Repairing the ducts in a subset of those homes cut air conditioning energy use by 18 percent, with a simple payback under two years.
A duct system pulling four times as much outdoor air into the house whenever the AC runs, in a climate averaging 71% relative humidity, is not an energy statistic. It is why the house feels damp.
A duct leakage test pressurises the sealed duct system to 25 pascals with a calibrated fan and measures the airflow needed to hold that pressure. The result is stated in cubic feet per minute per 100 square feet of conditioned floor area. Florida’s Energy Conservation Code sets the post-construction limit at 4 CFM25 per 100 square feet.
The 2023 Florida Building Code, Energy Conservation (8th edition) requires this on new construction, with two rough-in thresholds: 4 CFM25 per 100 square feet with the air handler installed, and 3 without it. Testing is waived only where ducts and air handler sit entirely inside the thermal envelope, which almost no existing Florida house does.
The code does not compel it on an existing home. A house built in 1998 was never tested against that standard, and one built in 2015 was tested once, before ten summers of attic heat went to work on it.
A return leak is worse because it pulls unconditioned attic air into the system rather than pushing conditioned air out of it. A supply leak wastes cooling you paid for. A return leak wastes it and adds heat, humidity, dust and attic insulation fibres to the air your family breathes.
Attic air in a Florida summer is hotter than the outdoor air and carries whatever is up there with it. Drawing it into the return means latent capacity that should be removing humidity from your living room is spent on the attic instead. The house cools eventually and never quite dries out, which is why sealing the return side first is usually the highest-value hour on the job.
A TLS technician measures the static pressure across your air handler and tells you which half of the system is costing you the air.
Florida attic ductwork fails because it lives in the worst environment in the house. Monitored Florida attics run roughly 20 to 24 degrees above outdoor air temperature under a vented dark shingle roof, and up to 40 degrees above ambient with poor ventilation. Heat, humidity, UV, sagging, compression and rodents then work on flex duct continuously for years.
A Florida Solar Energy Center study monitoring 21 houses recorded peak attic air temperatures reaching 117.7°F, and recommends designing for ambient plus 22°F under a vented shingle roof. Flex duct spends every summer afternoon of its life at that temperature, and both the plastic inner core and the foil-faced vapour barrier age for it.
Flexible duct only achieves its rated capacity when pulled taut and fully supported. A run that sags between hangers, or has been compressed past a truss, loses airflow disproportionately — a duct crushed to two-thirds of its diameter loses far more than a third of its air. Sag accumulates over years, which is why a system that worked when the house was new does not now.
The outer jacket on flex duct is the vapour barrier keeping attic humidity out of the insulation. Once it tears, splits or goes brittle, moist attic air reaches the cold inner core and condenses. Wet insulation loses its R-value, drips onto ceilings and grows things nobody wants in an air path.
Most duct systems in this market were built with tape at the collars and boots. Tape gives up first, and a branch loose at its collar dumps its whole output into the attic.
Florida attics host rats, squirrels and insects, and flex duct is easy to chew through and comfortable to nest in. A chewed run is not meaningfully repairable.
Flex duct in a Florida attic is generally serviceable for ten to twenty years, and the spread is almost entirely down to how well it was installed and supported on day one.
A TLS duct assessment is a booked appointment of about an hour in which a technician measures total external static pressure at your air handler, inspects every reachable run, boot and plenum in the attic, and leaves a written recommendation naming seal, repair or replace with the readings behind it. The estimate that follows is free.
Seal when the ducts are intact, correctly sized and leaking at joints and connections. Repair when the damage is confined to a few identifiable runs on an otherwise sound system. Replace when the ducts are past fifteen years old, when the vapour barrier has failed system-wide, or when the original design cannot deliver the air the house needs.
Sealing a duct system that was undersized in 1996 makes an undersized system airtight. Replacing a sound system because two collars came loose is an expensive way to fix two collars.
| Situation | What it needs | Typical cost | Why |
|---|---|---|---|
| Joints and collars leaking, ducts sound, sizing correct | Seal | $1,000 – $3,000 | Mastic over mechanical fastening at every connection. Highest return per dollar here |
| One or two damaged, chewed or disconnected runs | Repair | $79 – $650 per section | The rest of the system is sound. Replacing a whole run costs $600 – $900 |
| Vapour barrier failed on most runs, insulation wet or grey | Replace | $2,500 – $12,000 | Sealing a duct whose jacket has failed buys a season, not a decade |
| Ducts over fifteen years old and static pressure high | Replace | $2,500 – $12,000 | Age plus a high manometer reading is the clearest replace signal there is |
| One room never cools, rest of house fine | Repair or redesign | $79 – $650, or full replacement | Measure before spending. One crushed run, or an undersized return |
| Whole house under-supplied, returns undersized | Replace and redesign | $2,500 – $12,000 | Sizing cannot be sealed. The system has to be recalculated |
These are ranges, not quotes — your exact price is confirmed in writing after diagnosis and does not move after that.
Duct sealing is enough when the ducts are the right size, the insulation and vapour barrier are intact, and the losses are at joints, collars, boots and the plenum. Proper sealing means mastic applied over mechanically fastened connections, never tape. Expect $1,000 to $3,000 for a whole house here.
Mastic is a thick, brushable compound that cures to a permanent flexible seal and stays sealed at attic temperatures. It goes over the mechanical fastening — a screwed or banded connection first, mastic second — because a sealant is not a fastener.
The places that leak are predictable, and TLS seals all of them rather than the reachable half: the supply plenum at the air handler, every branch collar, every boot at a ceiling register, the return plenum and the filter housing.
A section needs repairing when the damage is local and the system around it is sound: a run chewed by rodents, a branch disconnected at its collar, a crushed duct behind a truss, or a torn outer jacket on one run. Repair pricing in this market runs about $79 to $650 per section.
Repair is the right answer more often than the industry admits, and the answer that costs us most to give. A single disconnected branch produces every symptom on the signs list above, and reconnecting it with a screwed collar, mastic and a strap costs a fraction of a re-duct. If your ductwork needs one run and a plenum seal, that is what the quote will say.
Replace the whole duct system when the failure is systemic rather than local: insulation wet or degraded across most runs, a vapour barrier torn in multiple places, duct past fifteen years of Florida attic service, or a design that cannot deliver the airflow the house requires. Full replacement in this market runs $2,500 to $12,000.
A replacement is a design job, not a swap. TLS sizes the new runs for the airflow each room needs, hangs them so they cannot sag again, insulates to R-8 for attic service, seals with mastic over mechanical fastenings, and re-measures the static pressure at the end rather than assuming it.
It is also the moment to correct what the original builder got wrong, because the attic labour is paid for once. If you are also considering AC replacement, doing both together is materially cheaper than eighteen months apart — and a new system on old, leaking ducts will never deliver the efficiency you paid for.
No. Duct tape is the one sealant that has been formally shown to fail on ducts. Lawrence Berkeley National Laboratory tested duct sealants under accelerated heat ageing and found that typical cloth-backed duct tape with natural rubber adhesive failed faster than every other sealant tested. Mastic is what actually holds.
The LBNL work by Max Sherman and Iain Walker exposed sealants to sustained temperatures around 93 to 100°C. The natural rubber adhesive and the backing were both identified as failure points, and the researchers concluded existing UL listings were not sufficient to establish durability.
A Florida attic is a slower version of that oven, running to 117°F and above every summer for fifteen years. Tape dries, the adhesive releases, and the seal opens at the joints that matter.
TLS installs galvanised sheet metal trunk and plenums with R-8 insulated flexible branch runs, every connection mechanically fastened and then sealed with mastic, and returns sized to the airflow the system actually needs. R-8 is the Florida code minimum for attic duct and it is what we fit as standard, never R-6.
Sheet metal trunk with flexible branches runs $4,500 to $9,000 against $2,500 to $12,000 for an all-flex system, and it outlasts flex because rigid metal does not sag, cannot be crushed past a truss and has no vapour barrier to tear. Flex earns its place on the branches, where it turns without fittings and runs quietly. Where a house has the attic headroom for a trunk, that is what we recommend; where it does not, an all-flex system properly hung and supported is a sound system for fifteen years, and “properly hung and supported” is doing the work in that sentence.
Support is where most of this market’s ductwork was let down. The installation standard for flexible duct is a support every four feet at most, sag no greater than half an inch per foot between those supports, and hanger material at least an inch and a half wide so the weight of the duct does not close it up. A run hung on plumber’s tape at eight-foot intervals meets none of that, and it is what a great many Florida attics have in them.
Returns are the other systemic fault, and they are the reason a whole-house re-duct is sometimes the only honest recommendation. A house with one central hallway return has no return path from the bedrooms, and no amount of sealing changes that. TLS sizes the return side to the airflow the equipment needs and gives every bedroom a way for its air to get back — a return in the room, a transfer grille, or a jumper duct over the ceiling — because a bedroom that cannot exhale cannot inhale either.
Duct replacement in Florida runs about $2,500 to $12,000 for a full residential system, or roughly $25 to $55 per linear foot installed. A 1,000 to 1,500 square foot home falls between $2,500 and $5,500; a 2,500 square foot home between $6,000 and $12,000.
Benchmarked against five Florida market sources, reviewed August 2026, for houses on both coasts. These are ranges, not quotes — your exact price is confirmed in writing after diagnosis and does not move after that.
| Job | Typical range | What moves the number |
|---|---|---|
| Full duct replacement — 1,000 to 1,500 sq ft | $2,500 – $5,500 | Number of runs and returns, and attic headroom |
| Full duct replacement — 1,500 to 2,500 sq ft | $3,500 – $8,000 | The commonest Florida house size, and the widest range here |
| Full duct replacement — 2,500 sq ft and above | $6,000 – $12,000 | Long runs, two air handlers, or a second storey |
| Sheet metal trunk with flex branches | $4,500 – $9,000 | Lasts longer than all-flex, costs more to fabricate and hang |
| Whole-house duct sealing | $1,000 – $3,000 | Number of connections and how much is reachable |
| Duct repair — per damaged section | $79 – $650 | Whether the run can be repaired or has to be replaced |
| Replacing a single duct run in R-8 flex | $600 – $900 | Length of run and difficulty of the attic |
| New supply plenum or coffin box | $750 – $1,200 | Fabrication, and whether the air handler connection is rebuilt |
| Duct leakage or pressure test | $200 – $450 | Standalone service. Static pressure on a call is free |
| Per linear foot, installed | $25 – $55 | Flex at the low end, sheet metal at the high end |
| Permits and inspection | $50 – $400 | Set by your county |
| Old duct removal and disposal | $100 – $300 | Volume of material and attic access |
An estimate for duct replacement is free, in your home, with no obligation. A diagnostic on a system that has stopped working is priced separately at $125, waived for Comfort Club members.
Whole-house duct sealing in Southwest Florida and Tampa Bay costs about $1,000 to $3,000, or roughly $1 to $2 per square foot of conditioned floor area. The price is driven by how many connections there are and how much of the duct system a technician can physically reach in your attic.
Sealing is the highest return per dollar on this page when the ducts are sound — the Florida research puts payback under two years against an 18 percent cut in cooling energy.
It is also the job most often quoted badly. A quote covering only the runs a technician could reach in twenty minutes is not a sealed duct system, and the difference does not show until the next bill. Ask whether the return plenum and air handler cabinet are included, and whether the result is measured. On a TLS seal they are, and it is.
The in-home visit, the static pressure reading and the written recommendation cost you nothing and commit you to nothing. Courtney books it while you are on the phone.
Most residential duct replacements take one to two days. A TLS crew lays drop cloths and puts shoe covers on before anything comes into the house, works from the attic, removes the old duct the same day and takes it away. You can stay in the house, and the air conditioning is off for part of each day.
Supply and return ducts in a Florida attic must be insulated to a minimum of R-8 under the 2023 Florida Building Code, Energy Conservation, 8th edition. Ducts elsewhere in the building require R-6. R-8 is the code floor rather than the sensible ceiling, and R-8 flex costs about $100 more per run than R-6.
The code sets R-8 for attic ducts and R-6 elsewhere, with reduced values for runs under three inches in diameter. Site-wrapped supply ducts outside the thermal envelope also require R-8.
A supply duct carries air at about 55°F through a space reaching 117°F, so the difference across that thin wall of insulation is more than 60 degrees for hours every day. R-8 does not stop that transfer, it slows it — air leaving the air handler at 55°F does not arrive at the register at 55°F, and the longer the run and hotter the attic, the wider the gap.
Manual D is the ACCA standard for sizing residential duct systems, calculating the size of every trunk, branch and return from the airflow each room requires. One room that is always hot is usually a duct problem, not an equipment problem — and across Florida the commonest single fault is a return that is too small.
A duct system is a distribution network with a fixed budget of air, and Manual D is the arithmetic that divides that budget correctly. It follows a Manual J load calculation, which establishes how much cooling each room needs before anything is sized. Systems designed from scratch are covered on our AC installation page; what matters here is an existing house that was never designed that way.
Undersized returns are endemic here. A great many Florida houses were built with one central hallway return and no return path from the bedrooms. Close a bedroom door and that room is pressurised, its supply air cannot get out, so less comes in — and it sits three to six degrees above the rest of the house every night. The fix is a return path, not a bigger air conditioner, and the number of homeowners sold a larger system for this fault is depressing.
The other faults we find are long flex runs where a short metal trunk should be, branches taken at right angles instead of a gradual takeoff, and registers placed to suit the framing rather than the room. All are correctable when the ducts are replaced, and expensive at any other time.
Where a room genuinely cannot be reached by ductwork — a converted garage, an addition, an enclosed lanai — a ductless mini split system solves it without touching the duct design.
No. TLS Air Conditioning does not offer duct cleaning. We seal, repair, replace and install ductwork, and that is the whole of what we do with ducts. The US Environmental Protection Agency states plainly that duct cleaning “has never been shown to actually prevent health problems” and does not recommend it routinely.
The EPA’s guidance is that ducts be cleaned as needed rather than on a schedule — where there is visible mould growth, vermin infestation, or genuine debris blockage. In the same guidance the agency recommends sealing duct air leaks as a measure that does save money.
A homeowner who calls about dust, odours or a house that never feels clean has usually been sold cleaning by someone, and the cause is very often a duct system pulling attic air in through gaps in the return. Cleaning removes the dust already in the system; sealing stops the next lot arriving. And where ducts have visible mould growth or wet insulation, cleaning is not the answer either — that duct is replaced.
The Temperature Selection Guarantee is a written TLS guarantee that every room in your home heats and cools evenly on ductwork TLS installed. Its material limitation is stated here rather than in a footnote: it applies to duct systems we designed and installed ourselves, and not to ductwork we inherited from a previous contractor.
“Every room in your home heats and cools evenly on ductwork TLS installed.”
Material limitation, stated in the same block as the claim. The guarantee applies to duct systems TLS designed and installed. It does not apply to ductwork inherited from a previous contractor. On inherited ductwork TLS will measure the static pressure, tell you which rooms are short of air and by how much, and quote the fix.
That limitation is not a get-out, it is the only honest way to write the guarantee. Even temperatures are a function of duct design, and we cannot guarantee arithmetic somebody else did. On inherited ductwork we will measure the static pressure, tell you which rooms are short of air and by how much, and quote the fix — but the guarantee attaches when we have built the system.
It sits alongside six other written guarantees, including No Change Order — the price never moves once agreed — and Better Than We Found It, which on a duct job means shoe covers, drop cloths and every scrap of old duct off your property. All seven are on our guarantees page.
Every person who comes to your home is a TLS employee, background checked, live scanned and drug tested. We do not subcontract duct work, which matters more here than almost anywhere in this trade — attic work is invisible once the hatch closes.
TLS Air Conditioning replaces, repairs and seals residential ductwork in ten Florida counties: Pinellas, Hillsborough, Pasco, Hernando, Manatee, Sarasota, Charlotte, Lee, Collier and DeSoto — 151 communities from Tarpon Springs to Naples. Duct crews are dispatched from the single Pinellas Park building, and the same people who quote your attic are the people who work in it.
Post-war Pinellas bungalows with almost no attic clearance are a different job from 1990s Cape Coral and Port Charlotte houses on slab with long runs to the bedrooms. Snowbird properties in Sarasota, Charlotte, Lee and Collier need saying up front — a house shut up through August with a leaking return duct is the classic route to a humidity problem you come home to.
Ductwork raises a different set of worries from equipment: how long it lasts, how much of the house gets pulled apart, and what order to do things in. These come up on almost every attic visit.
Call 941-269-3433 and ask for a duct assessment rather than a repair call — it is a different appointment length and Courtney will book it as one. After hours, that number still rings a TLS employee rather than an answering service.
The assessment is a static pressure reading, a look at every accessible run, and a written recommendation that says seal, repair or replace — with the reason and the number.
TLS Air Conditioning · Licence CAC1822364 · 6210 44th St N, Pinellas Park, FL 33781